Separating member for separating the tank bottom part the rest of the tank

ABSTRACT

The invention relates to a separating member for separating the bottom part of an electrolytic tank from the rest of the tank space in connection with the removal of solids ( 6 ) settled onto the bottom of the electrolytic tank ( 1 ). According to the invention, in the electrolytic tank ( 1 ) there are installed support and control members ( 10 ), which form the trajectory of the separating member ( 11, 21, 31 ), so that the separating member ( 11, 21, 31 ) can be inserted in the electrolytic tank ( 1 ) and removed therefrom via a space left in between at least one rear wall ( 7, 32 ) of the electrolytic tank ( 1 ) and the electrode ( 2 ) located nearest to said rear wall ( 7, 32 ).

The present invention relates to a separating member for separating thebottom of an electrolytic tank from the rest of the tank in connectionwith removing the solids created in the electrolytic tank.

In an electrolytic process, there are precipitated metals such ascopper, nickel and zinc onto the surface of cathodes provided in anelectrolytic tank, either starting from metal anodes that dissolve inthe electrolyte present in the electrolytic tank, or from metal ionsalready dissolved in the electrolyte. However, all solids are notprecipitated onto the cathode surfaces; these are for example preciousmetals and solid impurities contained in the electrolyte. Therefore,along with a metal refining process, on the bottom of the electrolytictank there are accumulated various solids that must from time to time beremoved from the tank, for instance because the solids contain valuableingredients, such as precious metals, or because a thicker solidsaccretion threatens the purity of the cathode obtained from theelectrolytic process.

Generally the solids accumulated in an electrolytic tank are at leastpartly very finely divided and only slightly heavier than theelectrolyte, wherefore it is difficult to separate the solids from theelectrolyte. In the course of the electrolytic process, it is extremelyharmful if the solids start circulating from the electrolytic tankbottom, because then the chance that the solids end up on the cathode isparticularly great, and this would result in a substantial drop in thepurity of the metal to be produced.

Generally the removal of solids accumulated on the bottom of anelectrolytic tank requires that the whole electrolytic process must beinterrupted, which reduces the efficiency per unit of time, i.e. theproductivity of the electrolytic plant. Thus the removal of solids mustbe made part of the replacing process of the electrolytes, i.e. anodesand cathodes, which makes the replacing complicated and slow andrestricts the solids removal to take place in a rhythm determined bysaid replacing exchange process. Moreover, a remarkable amount ofelectrolyte must first be removed from the tank and then returnedtherein, which generally has harmful effects on the electrolyte qualityand causes a lot of extra work. In the solids treatment system, therealso is conducted a remarkable amount of electrolyte, which must bereplaced with a new one and may be harmful in the further processing ofthe solids. In addition to this, the manual washing of the electrolytictanks makes the process clearly more labor-intensive and subjects theemployees to various health hazards, for instance owing to the effect ofsplashes sprayed from the tank and of the ingredients contained in thespray. Likewise, owing to the number of employees needed in the manualwashing of the tanks, it is often nearly impossible to automate thehandling of the electrolytes, which further increases the need for laborin the electrolytic plant.

The object of the present invention is to obviate some of the drawbacksof the prior art and to realize an advanced separating member suited inelectrolytic tanks in order to separate the electrolytic tank bottomfrom the rest of the tank, so that the removal of solids from theelectrolytic tank bottom can be carried out without essentiallydisturbing the electrolytic process. The essential novel features of theinvention are apparent from the appended claims.

According to the invention, in an electrolytic tank, advantageously inthe electrolytic tank walls, there are installed support members which,in addition to providing support, also guide the path of the separatingmember to be installed in the electrolytic tank. Said separating memberis arranged in the tank, substantially along the whole length thereof,essentially near to the tank bottom, for the duration of the removal ofsolids found on the tank bottom, so that the separating member separatesthe liquid electrolyte from the solids that are settled onto theelectrolytic tank bottom that are meant to be removed.

The separating member according to the invention is manufactured offlexibly connected structure elements which form an essentially sealedsurface, but which can also be bent in relation to each other. Thus theseparating member can be installed in the electrolytic tank without anyparticular aperture made in the tank, simply by conducting theseparating member onto the surface of the liquid electrolyte, andfurther under the surface, substantially near to the rear wall of theelectrolytic tank.

When the need arises to remove the solids accumulated onto theelectrolytic tank bottom, the separating member according to theinvention is first conducted to above the electrolytic tank, into aspace located in between the rear wall of the electrolytic tank and theelectrode located nearest to said rear wall, so that one end of theseparating member advantageously is substantially near to theelectrolyte surface. When the separating member is started to beconducted from the transport member into the electrolytic tank, tounderneath the electrolyte surface, the passage of the separating memberin the electrolyte is controlled by means of support and control membersattached in the electrolytic tank, advantageously in the electrolytictank walls. Said support and control members form the trajectory of theseparating member in the electrolytic tank. The support and controlmembers attached in the vicinity of the electrolytic tank bottom areinstalled in the tank at such a height with respect to the electrolytictank bottom that when moving the separating member at a speed determinedby the transport member, the solids found on the electrolytic tankbottom cannot start circulating due to the motion of the separatingmember, and thus the solids are prevented from remixing with the liquidelectrolyte.

Owing to the mutual flexibility of the structural elements of theseparating member, the proceeding direction of the separating member canbe changed from a substantially vertical direction in the vicinity ofthe rear wall of the electrolytic tank to a substantially horizontaldirection in the vicinity of the side walls of the electrolytic tank,when installing the separating member in the tank. Thus the support andcontrol members of the separating member can be arranged essentiallynear to both rear walls of the electrolytic tank, so that the separatingmember can advantageously be inserted in the electrolytic tank through aspace in the vicinity of one rear wall and removed therefrom through aspace in the vicinity of the other rear wall.

When the separating member according to the invention is placed in anelectrolytic tank, the separating member separates the part of the tankthat is located near the bottom from the rest of the tank, andsimultaneously it separates the solids found on the electrolytic tankbottom from the electrolyte needed in the electrolytic process.Consequently, the space left in between the separating member and theelectrolytic tank bottom can be cleared of solids without the solidsgetting a chance to be mixed into the liquid electrolyte present in therest of the tank. Thus the removal of solids can be carried out whilethe electrolytic process is in operation, and completely separately fromthe electrode treatment step. When the solids have been removed from theelectrolytic tank bottom, the separating member is removed from the tankby utilizing the support and control members attached in theelectrolytic tank, and shifted onto a separating member conveyorprovided outside the tank; said conveyor transfers the separating memberto another electrolytic tank, where a corresponding removal of solidsfrom the electrolytic tank bottom must be carried out.

The separating member according to the invention can be placed in theelectrolytic tank so that in between the separating member and theopposite rear wall, there is left a substantial clearing, so that theseparating member does not impermeably separate the solids locatedunderneath the separating member from the electrolyte located above it.In that case the separating member is not strained by the weight of theelectrolyte resting above it, and the space separated by the separatingmember is thus in connection with the space containing the electrolyte.

The separating member according to the invention can also be placed inthe electrolytic tank so that the separating member separates the spaceleft underneath the separating member, containing the solids, in asubstantially impermeable fashion. In that case the separating membercan advantageously be provided for example with a sealing agent filledwith some liquid or gaseous substance that seals the separating member,installed in the electrolytic tank and settled in place, against theelectrolytic tank walls.

In addition to the space located near the tank bottom, the separatingmember can also separate other spaces from the electrolytic tank, atleast the space located in the vicinity of one of the rear walls, sothat said space separated from the vicinity of the rear wall canadvantageously be utilized for example when removing the solids.

While using a separating member according to the invention, the supportand control members of the separating member can be installed in theelectrolytic tank, either so that when moving the separating member,there are used only those support and control members that are locatednear one of the rear walls, in which case the motion of the separatingmember takes place back and forth; or then in the vicinity of both rearwalls of the electrolytic tank there are installed support and controlmembers, so that the separating member is inserted into the electrolytictank through the space left in between the electrode located in thevicinity of one rear wall and said rear wall, and removed from theelectrolytic tank through the space left in between the opposite rearwall and the electrode located in the vicinity thereof, in which casethe motion of the separating member takes place always in the samedirection.

In the separating member, there can also be connected at least part ofthe electrolytic tank bottom scrubbing apparatus, in which case thescrubbing apparatus enters the electrolytic tank along with theseparating member. The scrubbing apparatus connected to the separatingmember can contain for instance washing nozzles or mechanical solidsremoval devices, in which case onto the electrolytic tank bottom part,there can be conducted some solids scrubbing agent, such as liquid orgas.

The invention is explained in more detail with reference to the appendeddrawings, wherein

FIG. 1 illustrates a preferred embodiment of the invention in partialside-view cross-section,

FIG. 2 illustrates the embodiment of FIG. 1, seen from the directionA—A,

FIG. 3 illustrates another preferred embodiment of the invention, seenin a partial side-view cross-section, and

FIG. 4 illustrates a third preferred embodiment of the invention, seenin a partial side-view cross-section.

According to FIGS. 1 and 2, in an electrolytic tank 1 there are placedelectrodes, anodes 2 and cathodes 3, in an alternating fashion, and themetal to be produced in the electrolytic process is precipitated on thecathode 3 by means of the electrolytic solution 4 provided in theelectrolytic tank 1. in the course of the electrolytic process, on thebottom 5 of the electrolytic tank, there are settled solids 6, whichmust from time to time be removed from the tank 1. According to theinvention, on the side walls 8 and 9 of the electrolytic tank 1, thereare installed support and control members 10. By means of said supportand control members 10, the separating member 11 is supported when it isplaced in the electrolytic tank 1, and it is conducted into the tank 1,so that the members 10 form the trajectory of the separating member 11.The separating member 11, which separates the electrolytic tank bottompart 12 containing solids 6 from the rest of the tank 1, is formed offlexibly interconnected structural elements 13, which enable anadvantageous bending of the separating member 11 while proceeding fromthe vicinity of the rear wall 7 to the vicinity of the electrolytic tankbottom 5.

In the embodiment according to FIGS. 1 and 2, the separating member 11is provided with nozzles 14, through which there is conducted liquid orgas into the bottom part 12 in order to facilitate the removal of solids6. The solids 6 and the liquid left in the bottom part 12, as well asthe liquid or gas fed therein through the nozzles 14, are removed fromthe electrolytic tank 1 via an outlet 15 provided on the electrolytictank bottom 5.

The embodiment according to FIG. 3 differs from the embodiment of FIG. 1in that the separating member 21 is installed in the electrolytic tank 1in a sealed fashion. Thus the bottom part 22, separated from theelectrolytic tank by means of the separating member 21, and the space 23left in between the separating member 21 and the electrolytic tank rearwall 7, together form a substantially closed space, so that the solids24 and the liquid found in the spaces 22 and 23 are discharged from theelectrolysis via the space 23.

In FIG. 4, a separating member 11 according to FIG. 1 is placed in anelectrolytic tank 1, so that support and control members 10 areinstalled in the electrolytic tank side walls 8 and 9 in order to ensurethat the separating member 11 is inserted in the electrolytic tank forinstance in the vicinity of the rear wall 7 and removed from theelectrolytic tank 1 in the vicinity of the second rear wall 32.

What is claimed is:
 1. Electrolytic apparatus comprising: anelectrolytic tank having a bottom and a rear wall; electrodes suspendedwithin the tank such that a space is formed between said electrodes andsaid rear wall of the tank, there being a bottom region of the tankbeneath the electrodes, a separating member movable within the tank, andsupport and control members within the tank for guiding said separatingmember along a path between said space and said bottom region of thetank, and wherein when the separating member is in said bottom region ofthe tank it separates the electrodes from a bottom part of said bottomregion of the tank and remains substantially above the bottom of thetank.
 2. Apparatus in accordance with claim 1, wherein the separatingmember is formed of flexibly interconnected structural elements. 3.Apparatus in accordance with claim 1, wherein when the separating memberseparates the electrodes from the bottom part of the bottom region ofthe tank a portion of the separating member extends within said space,there being a region of said space between the separating member and therear wall of the tank.
 4. Apparatus in accordance with claim 3, whereinthe separating member substantially isolates the bottom part of thebottom region of the tank and said region of said space from theelectrodes.
 5. Apparatus in accordance with claim 4, wherein theseparating member is substantially impermeable to liquid electrolyte. 6.Apparatus in accordance with claim 3, wherein the bottom part of thebottom region of the tank and said region of said space are incommunication with the rest of the tank.
 7. Apparatus in accordance withclaim 1, including a solids scrubbing apparatus attached to theseparating member in order to feed scrubbing agent to the bottom part ofthe bottom region of the tank.
 8. A method for removing solids from anelectrolytic apparatus comprising a tank having a bottom and a rear walland electrodes suspended within the tank such that a space is formedbetween said electrodes and said rear wall of the tank, there being abottom region of the tank beneath the electrodes, the method comprisingthe steps of: guiding a separating member along a path within said tankbetween said space and said bottom region of the tank such that whensaid separating member is in the bottom region of the tank it separatessaid electrodes from a bottom part of the bottom region of the tank andremains substantially above the bottom of the tank, and removing solidsfrom said bottom part of the bottom region of the tank when saidseparating member is in the bottom region of the tank.
 9. A method inaccordance with claim 8, wherein when the separating member separatesthe electrodes from the bottom part of the bottom region of the tank aportion of the separating member extends within said space and forms aregion of said space between the separating member and the rear wall ofthe tank.
 10. A method in accordance with claim 9, wherein theseparating member substantially isolates the bottom part of the bottomregion of the tank and said region of said space from the electrodes.11. A method in accordance with claim 10, wherein the separating memberis substantially impermeable to liquid electrolyte.
 12. A method inaccordance with claim 9, wherein the bottom part of the bottom region ofthe tank and said region of said space are in communication with therest of the tank.
 13. A method in accordance with claim 8, furthercomprising feeding scrubbing agent to the bottom part of the bottomregion of the tank.
 14. A method in accordance with claim 13, whereinthe scrubbing agent is a liquid.
 15. A method in accordance with claim13, wherein the scrubbing agent is a gas.